Igniter.



H. C. THOMSON L H. N. MCHAELSBN. IGNITER.

APPLIGATION FILED 33.15. 1.913,

Ll., Patented Aug. 11,1914.

lipplicetion iled February i5, 19M. Seial No. 7%,523

To all 'whom 'it may concern Be. 1t known that we, HENRY C. THoMeon and Haenen N. ittici-Limone', citizens, re

spectively, of ythe United Stnte and ot Nor` wey, anti ieeitlini, fesspectii'ely, in Boston, in the county ot ^l1iti'ollc,`itate of lvleesacliueete, and in Cantcni,'connty of Norfolk, llflnssuchnseits, lieve invented a certain ne.7

'and useful lzniirovernent in lgniters, ot'

which the following is a Speoilication, reference being had therein to the eccon'i'ienying drawings.

Uur invent-ion relzitee to spark producing apparatus or igniting devices designed to ignite the exploeive gaseous mixtures witliin the cylinder ol an internal combustion engine. More particularly it relates to iganother it i'clati'fs to e special formation of .ging parte :wronged to etiect the electric. conininnication tiel-Ween a cen-- ter-pin mounted in the casing' finti lending to one of' the liigli-teneion terminale ot, the induction coil, and :i contact member carried in tlieporcelain core and connected to the central Spark point ol the Jerk plug'.

The first i'ntntioneilA eetlu'e of our invention ser p1 to provide en etlicient nieane o supportingr said casing upon the spark plug ssliell, which means isein'oodied in n Single part, inexpensive in initial cost and in niofle of attachment to the casing which it snppoi'ts. Further the formation of such part is one which is intended to cooperate in more effectively securing the result which iS more especially the object of tlievsecond feature of my invention, as hereinafter mentioned..

The second feature serves to locuzite the point of engagement bet-Ween the exposed end of `the center-bai' and the contact zneniber in the porcelain core leerling to the Sperlf point, well Within the end of the porcelain core, and :it e point Whe-rein it is insulated luy said core lroni the `will olf epeili: plug heeel nut.

Both the above` mentioned teatureeiot om: invention eci-operate to secure liigli'flegiee of electrical isolation, relative, to the spark plug head not, of 'the exposed. or unprotected Aportion of. the eenterpin at or neer the point Where Seid exposed end ineliee angegernent With the seid Contact. in the porcelain ooi'e. ln ooneeqnence of which isolation, the leakage of the higliteneion current ernployed for producing the igniting sparite from sziid'exposed end ont the center pin and the spark plug shell is @essentially eliminated. At the saine time 'tl/ie simple oi'nian tion of said casing supporting ineens and the Simple motie of attaching the saine to the easing rendered possible by such formation coi'itz'ibiites to leseening the cost oi: inane- :feeture oif'tlio igniter.

@ur invention is shown in the (leanings which accompany tie specification, and forni :1 part oit this epplieetion.

'ln said drawings .Figure ll is a side elevation, partly in eection, showing the construetion oi' wir ignite?. v Fig. Q is e pien .vien

showing the element employed 'to support said casing with reference to the hotly of the spark plug. Fig. 3 is a. top View .of our igniter.

lliwing reference to Said'. figures, l represents the slieile oaf-'e spart: plug, on which shell carried one of the sparlipoints, 2, which ie in electrical connection with one terminal, 3, of the induction ooil, preferably by groimdi ig, es will be hereinafter setV forth. .in said shell located e een- Wi trai core, e, preferably of porcelain oi' other suitable insulating materiel, the upper or inner end olf-Which core ie conceved conionlly ci' cupped et 4a, preferably quite deeply as; shown in' said Fig. 3. Embedded in Seid porcelain core 4 anti extending; l0ngitnciineily therethrough is e conductor, terminating in, or connected at its lower, or outer' enel, Witlrtlie spark point, 6, enel, hei/ing its other, or inner end, in electrical connection with a. contact element adapted to engage tlie exposed end 14a of the centerpin, le, nereinefer mentioned; seid contact element being preferably embodied as a .quill 7 set- Witliin e snort axial extension from the cup or necess, 4a, piovidod at the inner end oit' the core. Ehe said porcelain or core', 4C. is seciireci in its assembled position in seid spark plop, body by ineens of the spark plug' heaelmut, 11, in ii'euel manner. Such heed-nut which also performs the function ot-e coil supporting element, as hereinafter set teeth, preferably formed till lil@

of a single metal stamped piece, and comprises a threaded neck, 11a, adapted to engage a correspondingly threaded seat 1n the spark plug shell, 1, which neck, 11, leads upwardly to a preferably hexagonal portion, 11b, above which extends a projecting portion, 11, which is secured to the base of the ignitcr casing 12. In the preferred form of igniter now being described said projectingportion 11c of the spark plug head nut is iared outwardly and is embedded within the material comprising the base of the igniter casing 12when the material o which the same is formed is in a plastic condition; said casing being composed preferably of electrically insulating material whichl may be molded or pressed into shape while plastic and thereafter solidies or hardens. By this construction the projecting portion of the spark plug head nut becomes permanently embedded in the material forming said base and through such embedded portion the spark plug head nut becomes inseparably attached tothe base of the casing, being capable of detachment only through the breakage of the casing.

Extending from the lower end or base of the igniter casing, 12, and lying within that position the spark plug head-nut above the neck, 11, is a conical or tapered projection, 13, hereinafter referred to as a pillar, through which axially extends a center-pin 14, whose outer or lower end, 14, projects beyond said pillar and is therefore electrically unprotected or exposed for a short distance. The upper or inner end, 1-11, ot saidl center-pin, 14, is connected with one terminal 15 ot the high-tension winding of the induction coil as by the connection, 10. The other terminal, 3, of the said high tension Winding, jointly with one primary terminal, 17, is connected to tue metal insert 8 provided with a binding screw, 1S, is in electrical connection with the spark plug shell, 1, and the spark plug head-nut, l1, through an external grounded circuit, w-a:, in a' manner understood by those conversant in the art of electric ignition. The other primary terminal 19 is connected to a similar insert 2O having a binding screw/21 for attachment to one terminal 22 of a battery and vibrator circuit not shown in the iigures, having its other terminal connected preferably through grounding to the screw 1S, Surroumling the pillar 13 is an annular chamber ot which the upper end is shown at 16, which is exteriorly bounded by a wall or lining 1lia formed of the insulatingmaterial lilling the interior of the spark plug head-nul, l1, lying above the neck, 11a, ot' the same. Such wall or lining 16t1 ot' said annular chamber 1G is substantially flush with, and forms a continuation of, the interior bore of the neck, 11a. Said annular chamber is, in consequence, of such diameter as to permit the cupped, or conical inner or upper end et' the porcelain core, ll, to freely enter within the saine. Said wall or lining 1Ga is commonly lormed during the process of attaching the spark plug head nut to thc casing through the molding of the projecting portion of the same into the base of the casing. During the process of such molding an excess of the plastic material required for such base is caused to be protruded from the base into said hexagonal portion of the head nut so as to interiorly line the same. p

The cup or recess, 4, on the top of the inner or upper end, 4f, of the porcelain core is so contoured and sized with respect to the contour and size of the pillar, 13, projecting from the base of the casing, 12, and lying within said annular chamber, 16, that said cupped core end, el, is adapted to fit over said pillar, 13, so as to permit the exposed end, 14, of the center-pin, 14, to enter within the cup or recess, el, at the end ot' the porcelain core, 4, sullieiently to bring the exposed end, 14a, of the center-pin, 1-1. into engagement with the quill, 7, located at the bottom of said cup or recess, il, and in electrical connection with the spark point, 5.

It will be evident that by means ot' the construction hereinl'iefore described nthere is secured an air gapbetu een the exposed end 14, ot' the center-pin, 1-l-,and that portion of the spark plug head-nut which is nearest adjacent thereto` ot' a length determined by the' peripheral distance from such nearest point of the inner wall of the spark plug head-nut 11 along the interior lining 16aL around the top edge of the cupped recess, 4, of the porcelain core and down into said cup or recess, l, until the exposed end, 141,of the center pin, 14, is reached. This length ot air gap so provided effectively secures the electrical separation or isolationy of the said exposed end, 111, of the center-pin, which is connected to the high tension terminal, 15, from the sparkplug head-nut 11, which is in grounded electrical connection, as hereinbefore described, with the other high tension terminal 3, ofthe induction coil. In consequence the leakage of high tension current between such exposed end, lll, and the wall `of spark plug head-nut, 11, which has been often l'ound to occur between such parts where a straight or rounded-top porcelain core has been employed, is practically eliminated. At the same time my col'istruction preserves all the characteristic features of simple construction and of a readily detachable engagement between the spark plug porcelain and. the centcrpin which s present in the prior igniters having the straight or rounded top porcelain. Furthermore the use oit a spark plug head-nut-having its upper part moldedinto the base of the igniter casing, and engaging the body of the spark plug through the threaded neck 11 integral With said upper part, provides a simple and reliable manner of supporting said casnng with respect t said spark body by reason of which economy in cost of construction may be realized, and one which is particularly resistant to the effect of the jarring or vibration commonly met With in the situations'where igniters are located,

ln addition the type of head-nut describes, and the manner of attaching the same to the casing provides a mass of insulating material forced upon said head-nut,

' embodying at one enda neck engaging the spark plug shell, and at the other a projecting pol tion permanently embedded in the material forming said base so as to be inseparably attached thereto.

2.' In an igniter, in combination with a spark plug having a spark plug shell, and an induction coil; a coil supporting casing embodying a base formed ot' solidified insulating material originally in a plastic condition' and a coil inclosing portion carried uponsaid base, and a spark plu head-4 nut supporting .said coil upon sai ''sparlr plug, said head-nut comprising a ,neck engaglngl the spark plug shell, a projecting portion permanently embedded in the material forming said base so as to'be insepavrably attached thereto, and an hexagonal 'portion conneeting'said neclr and said projecting portion; said hexagonalportion being i'nteriorlyI lined with insulating material integral with said base.

3. In ani iter, in combination, the centerV pm surroun ed by a projecting pillar of in- `5o sulating material, Aoutside of which is an an nular chamber, a core having its inner end cupped or recessed, and with the contact element located at the inner end of the cup or recess, and the edge or Wall lying around the cup or recess at the end of the core and entering Within the said annular chamber lying outside the said pillar of insulating maf terial. i

4. ln an igniter', in combination, a centerpin surrounded by a projecting pillar of in sulating material,l an annular chamber lying outside of said pillar, a core having `its inner end cupped or recessed with a contact element located 'at the inner or lower end of said cup or recess, and having an edge or wall surrounding the cup or recess at the end of the core and adapted to enter into said annular chamber and to lie outside said projecting pillar. l

5. In an igniter, in combination, a spark plug having a spark plug shell, an induction coil, a-casing' supporting saidcoil, said cas- 'ing having a center pin located in the base or' the-same and surrounded by a projecting pillar of insulating material a spark plug 'head nutA comprising.a portion embedded With the casing, an-hexagonal portionprojecting below said casing, said por- ,t-ions being interiorly filled with insulating' material, and a tubular neck, integral with the aforesaid' portions and engaging-the spark plug shell, the o ening in 'saiini- .neck being contlnued upwar ly through tliev said insulating material -iilling 'the upper porf tions of the head nut to form an annular chamber lying around said projecting pil lar, and a porcelain nr corehaving its inner end' cuppe Contact ele'mentlocated at the inner endo the cup Aor recess, the ledge or .wall surrounding the cup or recess being adapted to enter `into said annular chamber and tvo'lie outside the'said pillar. l

In testimony wher-ectl We aiX our signatures in presence of two Witnesses.

' HENRY C. THOMSON. i

y HAROLD N, MCHAELSEN. Witnesses:

NATHAN B. DAY, y ACHAI; F. RANDALL.

or recessed, and with a central 

